Asymmetrical Unity Horn

[Patrick Bateman]

Back in the day, I made a thread about asymmetrical Synergy horns here: https://www.diyaudio.com/community/threads/asymmetrical-synergy-horn.304489/

The idea has always been a bit fascinating to me, because:

1) asymmetrical horns can often have much better WAF. For instance, you can use asymmetrical horns on shallow loudspeakers, so that you don't have to rotate the entire enclosure.

2) I used to be fairly well known in car audio, and in car audio, nearly all of the cars running horns are using asymmetrical horns. I've long believed that it should be possible to improve on these designs, but the vast majority of them are built based on ideas from the 1960s and 1970s. Basically, car audio horns haven't evolved much since 1995 or so.

 

[Patrick Bateman]

Here's some pics of the waveguide and pics of the enclosure that I simulated it in, using ABEC

Note that the throat of the waveguide is off-center; this is what 'steers' the sound off-axis

 

[Patrick Bateman]

Here's the config file:

Source.Contours = {
zoff -1

point p1 2.58 0 2
point p2 0 13 0.5
point p3 1 14 0.5
point p4 0 15 0.5
point p5 0 16 1
cpoint c1 -33.94 0
cpoint c2 0 14

arc p1 c1 p2 1.0
arc p2 c2 p3 0.75
arc p3 c2 p4 0.25
line p4 p5 0
line p5 WG0 0
}

Throat.Angle = 25
Throat.Diameter = 32
Throat.Profile = 1
Coverage.Angle = 40 + 20*sin(0.5*p)^2 - 10*sin(p)^4 - 0.15*cos(p)^4

Length = 101.6

OS.k = 1.30

Rot = 3.26

Term.n = 4.03
Term.q = 0.996
Term.s = 0.7
;Term.s = 1.0 - 0.5*cos(p)^2

Mesh.Enclosure = {
Spacing = 127, 50, 127, 50
Depth = 200
;EdgeRadius = 38.1
;EdgeType = 1
FrontResolution = 12,12,12,12
BackResolution = 24,24,24,24
}

Mesh.Quadrants = 12
Source.Shape = 2

Mesh.AngularSegments = 64
Mesh.LengthSegments = 28
; Mesh.SubdomainSlices =
Mesh.InterfaceOffset = 8.0
Mesh.Quadrants = 12
Mesh.ThroatResolution = 4
Mesh.MouthResolution = 10

ABEC.SimType = 2
ABEC.f1 = 450; [Hz]
ABEC.f2 = 14400; [Hz]
ABEC.NumFrequencies = 51
ABEC.MeshFrequency = 1000 ; [Hz]

ABEC.Polars:SPL_H = {
MapAngleRange = -90,90,37
Distance = 3 ; [m]
Offset = 95
}

ABEC.Polars:SPL_V = {
MapAngleRange = 0,90,19
Distance = 3 ; [m]
Offset = 90
Inclination = 95
}

Output.ABECProject = 1
Output.STL = 1

Report = {
PolarData = "SPL_V"
Title = "Offset waveguide - Vertical"
Width = 1600
Height = 900
;MaxAngle = 0
;NormAngle = 0
}

 

[weltersys]

Note that the throat of the waveguide is off-center; this is what 'steers' the sound off-axis

Some time early this century I built a horn with a similar asymmetrical profile.
Unfortunately, the sound was not "steered" in the desired off axis direction, it was more like this:

Dave Gunness designed variable dispersion horns for EV, the coverage something like this:

Originally they had a very narrow diffraction slit:

later versions look more like this:

TLDR:
I don't think your horn will direct high frequencies in the direction you want enough to not have to to rotate the entire enclosure, but there are horn geometries that can .
Anyway, we're repeating ourselves..

Post in thread 'Shark Tank'

2021-10-12 10:29 pm

Based on Don Keele’s work leading to the 1983 white paper:
http://www.xlrtechs.com/dbkeele.com...rint) - Horn Covers Flat Rectangular Area.pdf
the JBL 4660 and the later Electro-Voice and Altec “Variable Intensity” high-frequency coverage patterns are symmetrical from side to side, but skewed front to back in such a way that the nominal “front” downward coverage angle is wider, while the “back” coverage angle is narrower.

The JBL 4660 drops from 110 degrees to 38 degrees from front to back, while the Electro-Voice Variable Intensity...

• weltersys

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